Electrochromic smart glass coating on functional nano-frameworks for effective building energy conservation

Electrochromic smart windows, with the ability to dynamically modulate thermal radiation transmission, are the key technologies to preserve energy expenditure for indoor lighting and air-conditioning. Despite receiving numerous exertions on design and fabrication technique, smart windows have rarely been commercially employed in the building industry due to unreliable lifetime, poor heat switching performance as well as high fabrication costs. Herein, we introduce a novel strategy in designing smart glass device, which focuses on the development of functionalized M_xSnO₂ nano-frameworks for electrochromic coating. The hybrid structures based on such nano-frameworks do not change the amorphous nature of electrodeposited tungsten trioxide (ɑ-WO₃) layer and therefore are able to preserve its excellent electrochromic properties. Novel hybrid nano-structures of M_xSnO₂/ɑ-WO₃ are able to encompass all desired features of a smart window, including the ability to block more than 95% NIR radiation in colored state while still allow about 80% of visible light transmittance in bleached state, rapid electro-optical response time of about 10 s and improved coloration efficiencies. More importantly, the advanced M_xSnO₂/ɑ-WO₃ nanostructures can also retain their structure and functionality for at least 1000 switching cycles due to the enhanced binding strength. In addition, the synthetic recipe of such functionalized nano-framework is facile and cost-effective, enabling the fabrication on any template type and size.